Heretofore, as one used for a base plate of laminated steel sheet in which films are laminated on a steel sheet, there is a surface-treated steel sheet as disclosed in Japanese Patent Laid Open No. 138786 of 1995 (Heisei 7).
However, the above-mentioned surface-treated steel sheet was difficult to be applied for uses such as in deep-drawn can, can end and others in which it is hard to be formed, since the performance of tenacious adhesion of the surface-treated steel sheet to thermoplastic resin film was not specifically examined. Particularly, in thin deep-drawn can and others, it particularly needs to be excellent in tenacious adhesion of surface-treated steel sheet to a film in order that excellent corrosion resistance can be secured even after forming.
Accordingly, it is the object of the present invention to provide a surface-treated steel sheet used as a base sheet for manufacturing a laminated steel sheet being excellent in tenacious adhesion of the surface-treated steel sheet to film after forming, while improving drawbacks of conventional surface-treated steel sheet.